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Mailport: February 2014

Mooring Design

Thank you for your review of the H2Out AVD diesel tank vent filters, and especially the tips on installation best practices (PS, January 2014). You’ve confirmed for me that I made the right move, and more importantly, that I actually installed the unit correctly on my boat.

Sailboats have a bit of advantage over their power cousins in that we have more high spots that can be used creatively. In my installation, the diesel vent line (fuel-grade hose) loops high inside at the transom and back down to the through-hull. Through the use of a check valve, air flows out, but intake air comes in through the AVD, which is attached to the underside of the deck; no additional support needed. The unit is readily available for inspection or replacement through the transom locker, and it is not in the way of any equipment that needs to go in or out. Love the H2Out AVD2 vent filter; kudos to Pindell Engineering.

Robert SenseneyContent, Rhodes (Chesapeake) 32Herring Bay, Md.

In this installation—which is suitable for diesel but not gasoline systems—the fuel tank breaths out directly overboard and breaths in through the silica-gel vent filter. The tee in the picture contains two check valves, which work to prevent contamination of the media during tank overfills. Unique to H2Out-maker Pindel Engineering, this vent installation method is not directly addressed by any code. The U.S. Coast Guard does not regulate diesel fuel systems, and the American Boat and Yacht Council (ABYC) is mute on this detail.

For gasoline systems, the regulations are quite clear: Vents must discharge outside the hull in a location where vapors cannot easily re-enter the cabin, with no exception for valve-regulated systems. The correct practice is to protect against sea water by a P-trap in the through-hull or a high loop. Practical Sailor discussed installation in the January and February 2013 issues.

Check valves in raw-water cooled exhaust installations should be monitored. The diesel-vent assembly should not rely on a check valve for preventing fumes from getting inside the boat.

Joker Valve Search

I’ve been looking for a rubber duckbill valve for a vented loop in a holding tank system, and it seems Buck Algonquin (www.buckalgonquin.com) has the right fitting. (My understanding is that the words “joker valve” and “duckbill” are interchangeable.)

Nigel Calder, in his book “Boatowner’s Mechanical and Electrical Manual,” makes an important point when he says “A vented loop in the discharge line will allow foul odors into the boat. It is best to attach a small hose to the vent and run it overboard.”

Forespar (www.forespar.com) has a replacement duckbill cap assembly (MF-841) that does not vent overboard, and they offer a vent barb assembly (MF-846) that does not have a duckbill. It seems to me that you would want a duckbill in the loop so as to not clog the holding tank vent.

For an installation where you are pumping waste overboard, Buck Algonquin’s vent arrangement would seem to be the right choice. The joker valve part number is 60VL75CV; it is the one used in the Buck Algonquin 00VL75 assembly.

Ted WassermanOutbound 46Marion, Mass.

Let us know how it works. An alternative would be to simply place a check valve in thew vent line itself. They are cheap, easier to clean, and easy to service inline; we often flush them with a hose or compressed air, and sometimes use acid for cleaning. And yes, a “duck bill” and a “joker valve” are the same thing.

Mooring Design

In response to your blog post, “Boat Mooring Upgrade Primer”: I devised a time-tested system to moor our 12,000-pound Ranger 33. An 1,100-pound concrete block with 6 feet of anchor chain was shackled to a 350-pound bounce block with 6 more feet of large anchor chain; one half-inch, three-strand nylon line led from the end of this chain to the boat. Two feet from the chain bottom, I threaded a large, fender-like float to lift about 3 to 6 feet of the rope and chain off the bottom. About 10 feet under water from the boat end, I placed 10 lead ring sinkers and flattened them enough so that they would not slide down the rope. This prevented the slack line from fouling the keel, rudder, or prop at low tides in calm conditions.

I allowed the nylon to collect a large growth of kelp and algae, which attracted fish and acted as a perfect, very squishy sea anchor. I threaded a small conical float—like those used on crab pots—about 5 inches wide by 12 inches long, to the mooring pennant and to each bridle leg, and placed a 3/8-inch stainless swivel (with a Nylox nut) at the bridle mooring-line junction.

In blows, the boat would pull against the two bridles alternately, reducing chafe. Firehose over the line at the bow worked for chafe protection. The floats acted as excellent rollers against the bow and kept the swivel and lines away from the gelcoat. When we left on trips, I snapped a regular mooring ball to the looped ends of the bridle for better visibility.

If I were to redo the system today, I would use a screw anchor and no chain at all.

Ken Russell

Rushwind, Ranger 33

South Puget Sound, Wash.

Furler query

In regard to your review of top-down spinnaker furlers (PS, January 2014): What about long time storage of the spinnaker wrapped around the torsion rope? Will the tight wraps damage the sail eventually? Also, as the tension of the halyard goes all in the tension rope, there does not seem to be a luff trim option.

Giovanni CirilloBuilding 46-foot performance cat

Unlike standard genoa furlers, top-down spinnaker furlers are not intended to be left hoisted with the sail on for long periods when they are not in use. When it is to be stowed, the sail should be furled and lowered. Leaving the furled sail in a bag/turtle and stowed below doesn’t harm it at all. As far as the luff is concerned, the only direct connection of the sail and the torque rope is at the head swivel. The sail’s tack is attached via a snap shackle or shackle to the furler drum or tack line, which can be used to tension the luff. See the accompanying illustration, which shows how a Ronstan top-down furler works. For more on top-down furlers, check out Part 1 and Part 2 of our test report in the January 2014 issue and in this issue.

Cleaners vs. Clear Vinyl

In response to your blog posts on caring for clear plastic on board (Dec. 10, 2013) and homemade mildew preventers (Oct. 14, 2013): Would the DIY mildew cleaner (TSP, baking soda, and sodium carbonate) solution harm the Strataglass, if some were to drip from the canvas onto the Strataglass window?

George ChamberlainIndefatigable, 1976 Whitby 42Port Charlotte, Fla.

The washing soda- and borax-based anti-mildew formulas were intended for cabin use. These do-it-yourself formulas are water-soluble, so although they might work to get a canvas dodger clean, they will likely rinse away from the top in the first rainstorm. Nevertheless, we have since tested these, as well as 3M and Goldshield anti-mildew formulas on Strataglass and Regalite. Applied in the normal manner and allowed to dry, all of these will cloud vinyl windows. However, if exposure is limited, and they are rinsed off before drying, no damage should occur. We have seen this same type of clouding damage caused by every highly alkaline cleaner; clear-vinyl windows should be cleaned and polished using only products specifically formulated for vinyl windows. At this time, our recommendation is to use Imar products.

Bleach on Strataglass

A recent issue had a short article on the effect of various cleaning agents on Strataglass (PS, December 2013). My copy of that issue is in New Hampshire, I am on my boat in Georgia, and I can’t find the article online. I am specifically wondering about using a diluted bleach solution to clean the canvas. Can you help?

Meg TorbertSeahoy, Passport 47Durham, N.H.

According to our very brief tests on Strataglass, bleach had no immediate effect on the clear vinyl, but it is known to cause fogging over time, with repeated use. See this month’s report on canvas treatments for more on products that can damage Strataglass.

Hose Clamps

The magnetism test that reader Ed Carter refers to in his Mailport letter was only part of the hose clamp test. A series of bench tests also determined the corrosion resistance (left), clamps thickness, and compression ability.

It is very laudable that you would undertake the testing of hose clamps, but there are several points in your article (PS, February 2013) with which I take issue. As a retired mechanical design engineer with a good deal of material experience, I know that the review of such a simple device is surprisingly complicated.

First is your conclusion that the magnetic properties indicate corrosion resistance. It is true that annealed austenitic stainless (304, 316, and several others) is essentially non-magnetic, that non-austenitic materials are magnetic, and that in general, the austenitic materials have better corrosion resistance. This, however, overlooks that some non-austenitic materials (such as 410 and 17-4) are magnetic and have sufficient corrosion resistance, and that the degree of cold work in the manufacturing process causes most common types of stainless (304 and 316) to become magnetic. This cold work does not reduce the general corrosion resistance of the materials. Both stainless 304 and 316 are available from the mill in varying degrees of cold work (annealed, 1/4 hard, 1/2 hard, and full hard), and any of these could be used for some parts of the clamp (from the stand point of corrosion), even though the higher hardness types would be magnetic.

For a demonstration, just touch your magnet to a piece of rigging wire, which is cold worked to about the full hard condition. Some manufacturers use cold-worked material where the parts must endure high service stress, such as rigging wire. Also cold work, to some degree, unavoidably comes from the fabrication process. For hose clamps, this could show up in the formed screw housing or the rolled thread on the screw. One manufacturer could anneal the parts after forming, which would return the part to the non-magnetic condition, while another manufacturer (using the exact same material) could leave his parts in the cold worked/magnetic condition. There would be no significant difference in general corrosion resistance. So the degree of magnetic attraction is not a valid indication of corrosion resistance.

Another point about corrosion that appears as surface rust shortly after subjecting the item to corrosive conditions is that during the fabrication process, the tools (drills, shears, etc.) that come in contact with the parts cause small amounts of iron particles to be transferred to the part. It is common to have this iron removed at the end of the fabrication using processes called passivization or electro-polishing. Parts that get less of this post processing will rust a little, but this is actually just the iron particles rusting. It looks bad but has no detrimental effect on the general corrosion of the part. Only a detailed examination can tell the difference between surface rust and general corrosion early on.

The bottom line is that in most cases, hose clamps do not fail from general corrosion, but from stress corrosion cracking (SSC) at the inside corners of a slot in the band where the screw engages the band. The T-bolt and ABA types should have a distinct advantage here. We also frequently see massive corrosion of the screw, but this usually doesn’t cause failure of the clamping function, just the inability to release the screw. I have several times seen clamps where the screw was unusable due to corrosion of the head, but the clamp was still holding tight on the hose.

SSC happens when three conditions are present: a susceptible material, a corrosive environment, and high static stress. Since 304 and 316 are susceptible (some other types of more expensive austenitic steels and titanium are not) and boats live in a corrosive environment, then we should reduce the static stress whenever possible. For hose clamps, this means not torquing the screw excessively. Since for most critical hose clamp applications the pressure is less than 2 psi, the screw torque to seal is very low, and, actually the fit of the hose on the nipple will often prevent leaking. I have seen numerous examples of a clamp band completely broken, and there was no leaking at the joint.

The additional important goal of the clamp is to keep the hose from pulling off the nipple. Unlike the presumption of your article, this should be the lowest screw torque that reliably prevents the hose from being pulled off the nipple – thus protecting the clamp from sudden catastrophic failure of the band due to SSC.

My suggestion for installation is: tighten the screw just snuggly; take a healthy pull on the hose; if there is no detectable motion, it is tight enough; if motion is detected, increase the screw torque a little and repeat the pull test.

Ed CarterBold Venture, Islander 37Seabrook, Texas

Excellent letter. We’ve covered most of the stainless topics before, but you’re absolutely right about the pitfalls of the magnet test, and we should have mentioned them in the article. However, we still believe that for many marine products, the magnet test is useful for the average consumer.

The recommended torque for hose-clamp screws that is stated in the article is consistent with what you are saying, but in our experience, this won’t always work with exhaust hose, which is the size that we tested.

Frothy Coffee

In regard to your January 2014 article on coffee-making methods: I would like to recommend two products to sailors who appreciate a good espresso, latte, or mocha on board. First, the MiPressi Twist, (www.mypressi.com), which is a compact and portable espresso brewer that needs only a little boiling water and NO2 cartridges (whipped-cream chargers). It makes very good espresso without the weight and high electrical demands of a traditional espresso machine. Second, we recommend the BonJour Caffe Froth Maximus Milk Frother, which is available from Amazon.com and many other online sources. It looks like a tall French press and does an excellent job of frothing milk without using a steamer wand. (Tip: For best results, go slowly.)

Rusty GesnerOn a Whim, Macgregor 26SPortland, Ore.

Coffee Tips

In response to your coffee article (PS, January 2014): I found that a collapsible silicone funnel, used with a Chemex coffee filter, works well for making coffee on board. (Both are easily available from online retailers and some big-box stores.)

I put a thermos in the galley sink, then put the funnel in the thermos opening. It’s fairly stable and easy to clean up. You do have to stand there to pour water from the kettle over the grounds though. The funnel is flexible, cheap, and takes up almost no room. I tried the Chemex coffeemaker first, but the glass carafe broke the first time out, despite the fair weather cruise. Nothing glass on my boat ever again.